Background: Caries inhibitory effect of fluoride has been known for about a century. The use of mouthrinses as a vehicle for applying fluoride in a self-administered preventive program was first proposed by Bibby et al. in 1946. Since then sodium fluoride (NaF) mouthrinses have been used extensively as a caries-preventive measure. Aim: To determine the effectiveness of NaF mouthrinses in the prevention of Dental Caries through a systematic review. MaterialsandMethods: A search strategy for the review was carried out according to the standard Joanna Briggs Institute systematic review methodology. An electronic search was carried out in PubMed, Medline, Google Scholar, and Cochrane Library from 1970 to 2012. Hand search was conducted through the reference list of articles. The main intention of our investigation was to check the amount of reduction in clinical dental caries. Of 657 articles originally identified, 35 records were considered potentially eligible and sought for further assessment. Results: A total of 28 articles met the inclusion criteria and were assessed independently for methodology and performance. Randomized control study design was followed in 17 studies mainly at evidence level; 2 with a preventive fraction ranging from 16% to 65%. The reported mean annual caries reduction among adolescents was 0.76. Conclusion: Daily or weekly NaF mouthrinses had a significant caries reduction among adolescents. Daily and weekly/fortnightly rinse programs showed an average of 39% fewer decayed-missing-filled-surface. Daily use of NaF had a slightly higher caries reduction rate. Not enough data are available to show the effect of fluoride mouth rinsing programs on deciduous dentition.

Caries inhibitory effects of fluorides have been known for about a century. For nearly 30-40 years following the pioneering work of Dean et al. it was generally believed that the most significant caries preventive effect of fluoride was preeruptive. Preventive measures based on this assumption included fluoridation of public water supplies and supplying fluoride in salt or milk or in tablet form to children. The above approach, that is, systemic use of fluorides as an important caries preventive method, is no longer accepted because the preeruptive caries preventive effect is almost nonexistent. [1]

In the early 1940s, it was appreciated that tooth enamel could take up fluoride ions from water solutions and that this renders the enamel more resistant to acid attack. Over the next 50 years this topical method has proved very successful in preventing dental caries, and many permutations and combinations of the concentration of fluoride in the solution, the type of fluoride compound used, and the frequency and mode of application have been studied. [1]

The classical method of topical fluoride application developed by Knutson is not practical for general use because it demands too much time and manpower. Alternative feasible fluoride delivery systems, such as mouth rinsing and brushing with fluoride toothpaste, have therefore been developed. [2] As with most of the early investigations into fluoride and caries, the first trial of fluoride mouthrinses were carried out in the United States of America. Since then, results of clinical trials from at least 14 different countries have been sufficiently favorable for dental public health officials to adopt fluoride mouth rinsing as the main alternative to water fluoridation for the prevention of dental caries in many areas of the world. [1]

The first test of fluoride mouthrinse was conducted in the 1940s; however fluoride mouthrinses gained much attention during the early 1960s, when the effect was extensively evaluated in well-controlled clinical studies as well as in field trials on school children in Scandinavia, particularly Sweden. Most of these studies and programs were based on weekly supervised rinsing with a neutral 0.2% sodium fluoride (NaF) solution. [3] Nearly all investigations in the 1960s using fluoride rinses involved children residing in areas with below optimal levels of fluoride in drinking water. Reports published during the 1970s demonstrate significant caries reduction benefits from fluoride rinses even in areas with an optimal concentration of fluoride in the drinking water. [4]

Published literature on the use of fluoride rinses in children residing in fluoridated communities indicates that cariostatic benefits provided by fluoride rinses are additive to those derived from community water fluoridation. [5] Even today undisputedly, as during the past 75 years, the best individual defense against dental caries remains the judicious use of fluorides. Perhaps the most important element in producing marked cariostasis is the frequent provision of low concentrations of fluoride to teeth and dental plaque. Special attention must be given to the development of self-applied topical fluorides since these do not incur the problems of insufficient and expensive professional manpower requirements. [5]

The incorporation of fluorides into the mouthrinses appears a logical and practical approach to the problem of delivering fluorides to a large number of persons. A large proportion of the global population use dentifrices and mouthrinse for oral hygiene. Various concentrations, compounds, frequency of rinsing etc., which offers diverse percentages of caries reduction in different types of dentition, have been reported. This systematic review was thus undertaken to critically analyze published literature on the effectiveness of NaF mouthrinses on the prevention of dental caries.

Aim

To determine the effectiveness of NaF mouthrinses in prevention of dental caries through the analysis of literature.

Materials and methods

The search strategy for the review was carried out according to the standard Joanna Briggs Institute (JBI) critical appraisal checklist for systematic reviews. [6] The electronic search was carried out in PubMed, Medline, Google Scholar, Cochrane Library, and articles published from 1970 to 2012 (over the past 40 years) were selected. The search terms were NaF mouthrinses, NaF and dental caries, NaF mouthrinse in the reduction of dental caries, the effectiveness of NaF mouthrinse. A total of 613 records were identified as abstracts or full-text articles and were retrieved.

Selection, screening, and inclusion of the manuscripts were performed by the first three authors. Only studies published in English language were considered due to the virtual absence of research published in other languages as resulted from preliminary electronic database searches. Gray literature was consulted, and their inclusion was through mutual discussion by all the authors.

During the first level of screening, as multiple databases were searched separately, the records were initially checked for duplicates and 44 records were excluded due to duplication. At the second level of screening, 394 manuscripts were excluded as they had various combinations of mouthrinses beyond the scope of this review. Further 174 records were eliminated as the outcome of the intervention in those records was not dental caries.

The main outcome of our investigation was a reduction in clinical dental caries followed by mouth rinsing with NaF mouthrinses alone. Hence, a total of 35 records were considered potentially eligible and sought for further assessment as shown in the Flow Chart 1.

These 35 records were critically appraised by the first three authors based on JBI critical appraisal checklist for systematic reviews. [6] The authors individually evaluated each study on a checklist provided by JBI Reviewers' Manual: 2011 edition. [6] Those records with unanimous acceptance were included; in the event of a tie-breaker situation, mutual discussions enabled inclusion/exclusion. Seven records were rejected because of the disagreements for inclusion by the authors in aspects of methodology, intervention, and outcome even after discussions. Hence, a total of 28 records were finally included in the systematic review.

Results

Total number of studies appraised critically was 35; seven studies were excluded due to lack of consensus among the authors. Of the 28 studies that were included in the systematic review, it was found that studies were conducted during 1971-2012. Further analysis of literature revealed that mainly two concentrations of NaF solutions have been used for mouth rinsing (0.2% NaF solution for weekly rinse and 0.05% NaF solution for daily use). NaF solution at 0.2% concentration weekly rinse resulted in caries reduction of 15-65.5% were as 0.02 NaF solution daily rinse resulted caries reduction over a range of 48-67%. A total of 10 studies were conducted upon permanent dentition with caries reduction range of 15-67%. Analysis of study designs as a focus of our investigation revealed that 17 studies were randomized control trials (RCTs). The sample size ranged from 71 to 2900 as shown in [Table 1].

Table 1: An overall analysis of the literature on included studies in this review

The studies were further analyzed based on the study designs, it was found that the maximum number of 17 studies followed RCT design, retrospective cohort designs were six, longitudinal observational studies were five. The JBI level of evidence was followed in this review as shown in [Table 2]. Most of the RCTs conducted had level; 2 evidence. These studies had a preventive fraction ranging from 16% to 65% and had a weighed mean decayed-missing-filled-surface (DMFS) reduction of studies of 0.76. Mean DMFS reduction for studies, which had intervention in control group other than placebos was 0.44 whereas studies, which had placebo for control groups had mean DMFS of 0.63. Retrospective cohort studies had caries reduction ranging from 20% to 54.2% whereas longitudinal studies had caries reduction ranging from 15% to 19.9%. Level of evidence in these studies was mainly Level; 3. The results of all these 28 studies are compiled in [Table 3].

In 1940s, only a few years after the first controlled community water fluoridation studies began, Bibby and others conducted a clinical trial in which dental students rinsed with an acidified NaF solution. Although use of the rinse failed to have an effect on caries, possibly because of the low concentration of fluoride, the concept of a fluoride containing therapeutic mouthrinse was born. [5]

A total of 657 articles were retrieved and 571 records were excluded at various levels of screening and a total of 28 records sought for detailed analysis. Analysis of records shows the overall percentage of caries reduction varying from as low as 15% to as high as 67%, this diverse reduction in caries made us to further analyze the records. Analysis of literature in terms of the effect of NaF mouthrinse on type of dentition revealed that two studies were conducted exclusively upon primary dentition these studies have begun when the subjects were around 3 years and ended when they were 6 years, reporting 0.45 new DMF surfaces per year. Maximum literature was found during mixed dentition period and in most of these studies, rinsing started in primary dentition and continued till subjects were 12 years old, the caries reduction was found to be 20-66.3%. A clearer picture of caries reduction was observed in permanent dentition from 15% to 67%.

Most of the literature points to a RCT study design where we found caries reduction of 25-67%. There were around six retrospective studies, which had a caries reduction ranging from 20% to 65.5% and the five longitudinal studies showed caries reduction of 15-19.9%.

This systematic review has focused only on NaF mouthrinses (no combinations) and its effect on reduction in clinical dental caries. The preventive fraction for RCTs was 16-65%, which is in contrast to the findings of a systematic review conducted by Marinho etal. and Twetman etal. [7],[8] The wide range obtained in this review would be possibly because of the inclusion of studies which has consistently given lesser preventive fraction values. The higher reduction values were obtained when NaF rinsing was performed on twice daily basis. Studies having lesser concentration NaF (0.05%) had no significant reduction in DMFS scores. One study by Ripa LW at evidence Level; 1 conducted over a period of 7 years published thrice reported varying preventive fractions of 30%, 55%, and 45% over 5, 6, and 7 years, respectively. [9],[10],[11] The reasons for such a trend need to be further analyzed.

Mean DMFS reduction for studies, which had intervention in control group other than placebos was 0.44 whereas studies, which had placebo for control groups had mean DMFS of 0.63.

Twelve studies were observational studies falling at level; 3. Since these are observational studies, preventive fraction could not be calculated. The sample size ranged from 120 to 2000 and the reported caries reduction ranging from 15% to 54.2%.

A study conducted by Driscoll etal., reported that children who used only NaF mouthrinse had a maximum reduction of 3.57 DMF surfaces per child, an average of about 0.45 new DMF surfaces per year. [12] Whereas in our analysis we found that nine RCTs, which were under supervision showed a mean DMFS reduction of 0.75 whereas nonsupervised fluoride mouth rinsing programs resulted in a reduction of 0.52.

A 2 years retrospective cohort study proposed that there is an additional caries protective effect of weekly fluoride rinsing whether or not combined with gel applications once every 3 months in a population exposed to fluoridated toothpaste and optimally fluoridated community water supply. [13]

A study demonstrated that weekly and daily mouth rinsing both provided significant caries-preventive benefits beyond those already accrued from consuming optimally fluoridated drinking water, both procedures were effective in reducing dental caries incidence on all tooth surfaces. [14] In addition, another study suggested that the most effective and realistic program for the prevention of permanent tooth caries consists of the continuation of a FMR program until the end of junior high school because permanent teeth continue to erupt during this period. [15]

The preventive effect of topical fluoride against dental caries begins during early stages of the eruption. Several studies suggest that topical fluorides are more effective when applied to newly erupted teeth than to teeth that have been in the mouth for several years. Initiation of FMR among preschool children is important in preventing caries of the first primary molar, which has the highest risk for dental caries, erupts during nursery school days, it is critically important to start the FMR program from at least this time point. In addition, the FMR program should be continued until the end of junior high school because permanent teeth continue to erupt during this period. Therefore, the most effective and realistic program for the prevention of permanent tooth caries consists of the use of a FMR beginning at 4 years of age and which continues until graduation from junior high school. [15]

In addition, enforcement of FMR among junior high school children is important in preventing caries in second molars. Many reports have shown that fluoride use during the period of permanent tooth eruption is very effective for caries prevention. [16]

The caries status of individuals before introducing the fluoride program is also important because people with a high level of caries take the most advantage and exhibit a maximum reduction in caries. [17]

To summarize our finding, very limited data are available to clearly demonstrate the effect of mouth rinsing on deciduous dentition. Though published literature suggests that fluoride mouth rinsing programs should be initiated during preschool years, there is a lack of evidence regarding the same. In addition, studies on this group need to be carried out to draw a further conclusion.

Conclusion

In this present review, we have found evidence that daily or weekly NaF mouthrinses had a significant caries reduction among adolescents. Daily and weekly/fortnightly rinse programs showed an average of 39% fewer DMFS. Daily use of NaF had a slightly higher caries reduction rate. Not enough data are available to show the effect of fluoride mouth rinsing programs on deciduous dentition.[35]

Leske GS, Ripa LW, Sposato AL. Posttreatment benefits from participation in a school-based fluoride mouthrinsing program: II. Results after three to five years of rinsing. J Public Health Dent 1982;42:222-7.

Ripa LW, Leske GS, Sposato A, Rebich T. Supervised weekly rinsing with a 0.2 percent neutral NaF solution: Final results of a demonstration program after six school years. J Public Health Dent 1983;43:53-62.